All stages in the life cycle of ticks tend to damage the skins of afflicted animals and thereby spoil the state of the skins with the consequence that cattle hides and sheep skins intended for the manufacture of leather and sheep skin are reduced in quality. Furthermore, the ticks may facilitate the transmission of disease to the afflicted animal, and the general state of health and the quality of flesh of the animal may be detrimentally affected.
Belgian Pat. No. 816,760 describes certain 5-(substituted phenyl)-3-(alkyl)-1-(alkyl)-1,3,5-triazapenta-1,4-dienes as broad spectrum parasiticides.
We have now found that certain 5-(substituted phenyl)-3-methyl-1-(heteroaryl)-triazapenta-1,4-dienes have particularly useful acaricidal properties, and are thus very useful in destroying one or more stages in the life cycle of ticks which tend to infest the skins of animals such as cattle. They may also have insecticidal properties, particularly against plant insects such as pea aphids (hemiptera).